Published online before print August 17, 2009
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B in THP-1 monocytic cells involves pertussis toxin-insensitive G
14 and G
16 signaling cascadesDepartment of Biochemistry, the Molecular Neuroscience Center, and the Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
1. Correspondence: Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China. E-mail: boyung{at}ust.hk
ABSTRACT
Agonists of CC chemokine receptor CCR1 contribute to the pathogenesis of autoimmune and other inflammatory diseases, possibly via the regulation of the transcription factor NF-
B. CCR1 and CCR2b have been demonstrated to use PTX-insensitive G
14 and G
16 to stimulate PLCβ in cotransfected cells, and G
14 and G
16 are capable of activating NF-
B. The coexpression of G
14, G
16, and CCR1 in human monocytic THP-1 cells suggests that CCR1 may use G
14 or G
16 to induce NF-
B activation. Here, we demonstrated that a CCR1 agonist, Lkn-1, stimulated NF-
B phosphorylation via PTX-insensitive G proteins in THP-1 cells. Lkn-1 also mediated IKK/NF-
B phosphorylations in HEK293 cells overexpressing CCR1 and G
14/16. Using various kinase inhibitors, Raf-1, MEK1/2, PLCβ, PKC, CaM, CaMKII, and c-Src were found to participate in Lkn-1-stimulated IKK/NF-
B phosphorylations in THP-1 and transfected HEK293 cells. Although c-Jun N-terminal kinase and p38 MAPK were activated by Lkn-1, they were not required in Lkn-1-induced IKK phosphorylation. The ability of CCR1 to signal through G
14/16 thus provides a linkage for chemokines to regulate NF-
B-dependent responses.
Key Words: chemokine leukotactin-1 G protein inhibitor
B kinase signal transduction